Apr 17, 2024 - Science

The 2024 Cicadapocalypse won’t be as apocalyptic as you think

Data: USDA and University of Connecticut; Map: Will Chase/Axios

In 2024, a double brood of periodical cicadas will appear across the U.S. Some have called the emergence a "cicadapocalypse," but is it really?

Why it matters: Axios Visuals fact-checked the insect hype and found that no matter how you crunch the numbers, 2024 will likely offer just a taste of the cicada spectacles to come.

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What's happening: There are 15 surviving periodical cicada broods, each identified by Roman numerals. This year is the first time in 221 years that Brood XIX (on a 13-year cycle) and Brood XIII (on a 17-year cycle) will emerge together.

Reality check: A 13-year and 17-year brood emerging at the same time is called a co-emergence, and they're fairly common, occurring every 5–6 years.

  • Adjacent co-emergences, where the two broods overlap geographically, are less common, happening every 25 years on average.
  • Don't confuse cicadas with locusts. Although both insects come in great numbers, cicadas do not swarm, they are not a plague and you should not kill them.
Graphic: Maura Losch and Kavya Beheraj/Axios

By the numbers: Axios Visuals calculated three metrics that could determine when the true cicadalanche will come.

(1) We estimate that the most cicadas will emerge during the Brood XIX and Brood X co-emergence in 2089, with over 15 trillion.

  • According to John Cooley of the University of Connecticut, it's "extremely hard to estimate the population sizes of periodical cicadas."
  • But if we assume 1 million cicadas per acre — a figure that comes from a census of the 1956 Brood XIII emergence — and 10% of the land area of affected counties occupied by cicadas, it yields trillions of cicadas for an emergence.

(2) The largest population affected will be the Brood XIX and Brood X co-emergence in 2089, with over 56 million people affected (by today's population), according to the USDA's lists of affected counties for each brood.

(3) The most cicadas per capita, over 1.7 million per person, is estimated during the Brood XXIII and Brood IX co-emergence in 2105.

Yes, but: Take all of these numbers with a large grain of salt. These figures are useful for comparisons between broods, but all of the numbers used in these estimates are extremely rough approximations.

The bottom line: No matter how you measure it, there's no need to bug out this summer — wait until 2089 for the ultimate cicada spectacle.

What they're saying: Zoe Getman-Pickering, an ecologist at UMass Amherst who has studied periodical cicadas, told Axios that an emergence this large will have "massive, complex and cascading impacts on the ecosystem."

  • Getman-Pickering and her collaborators found that birds switch their diets to chow down on cicadas during an emergence.
  • "When the birds changed their behavior to eat cicadas, the caterpillars that the birds normally eat were allowed to grow and thrive. Caterpillar populations doubled, and the amount of damage they did to their host trees doubled as well."

What's next: Periodical cicadas use climate-related cues to tell time, and increasingly unpredictable weather caused by climate change may confuse cicadas into emerging off-cycle.

  • When cicadas emerge early or late, they lack safety in numbers and are quickly gobbled up, threatening the population. Higher temperatures in the future will also stress cicadas.
  • Getman-Pickering told Axios that this means a future with decreasing populations, shrinking ranges and the possible extinction of smaller broods.
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